When it comes to heart disease, it may not be what pill you take, but how regularly you take it that is important. The finding controversially implies that so long as patients stick to a daily regime, they would do just as well with a placebo.

Bradi Granger of Duke University in Durham, North Carolina, and her colleagues re-analysed the results of a clinical trial involving nearly 7,600 heart-failure patients who were testing an experimental angiotensin receptor blocker (ARB), which relaxes blood vessels and lowers blood pressure.

Patients who took their pills every day halved their risk of dying by the end of the study, compared with those who skipped pills, Granger's team found, regardless of whether they took the drug or a placebo. Those who stuck to their pills were also less likely to spend time in hospital, she revealed this week at the American Heart Association meeting in New Orleans.

Experts suspect that those who stick to their medicine are also more likely to stick to other heart-healthy activities such as regular exercise, good diet and not smoking or drinking. These behaviours alone probably outweigh the physiological effect of the drug.

If doctors could identify those patients who are unlikely to take their drugs regularly, Granger believes that they could be targeted with education or social support that would encourage them to follow a healthier lifestyle.

"It is a direction people are taking," agrees Hayden Bosworth who studies patient motivation at Durham Veterans Affairs Medical Center in North Carolina. Some researchers, for example, are examining whether there are biochemical tests that would reliably show whether people are taking their drugs regularly.

Place for placebos

The drug in the recent study is called candesartan cilexetil and is marketed in the US by AstraZeneca as Atacand; it and many other drugs in its class are routinely used to treat high blood pressure. Cardiovascular disease, including high blood pressure, heart attacks and strokes, accounts for nearly 30% of total deaths in the world.

Two other earlier investigations have also shown that patients with heart disease get benefits from taking a regular placebo that almost match those provided by beta-blockers or lipid-lowering drugs. But researchers have struggled to explain exactly what is different about those who follow their doctor's instructions compared with those who flout them.

Another, more controversial, implication of the new results is that those people who are diligent about taking their drugs and following a healthy lifestyle might reap the same benefit if they cut their dose or switched from active drugs to a cheaper placebo. "It's definitely worth a study," Granger says.

A separate study published last week in The Lancet questioned the effectiveness of another widely used blood-pressure-lowering drug, a beta-blocker called atenolol. In an analysis of nine earlier studies, the drug was found to be less effective than other drugs and no better than a placebo at reducing deaths from heart attacks1.